The present invention relates to a device for the suspension and for roll stabilization of motor vehicles.
Active chassis systems which operate in conjunction with a hydropneumatic suspension and displace hydraulic medium from the hydropneumatic spring struts on one side of the vehicle to the hydropneumatic spring struts on the other side of the re vehicle through one or more displacement units in order to thereby influence the rolling angle of the vehicle body are conventional. In these systems, a hydropneumatic suspension replaces either a conventional vehicle suspension or its stabilizers.
A system in which a hydropneumatic suspension replaces a conventional suspension in a vehicle body is described, for example, in German Published Patent Application No. 39 36 987.
This system is characterized by the fact that it actively counteracts rolling and pitching motions of the vehicle by actively displacing hydraulic medium directly between the support elements on different sides of a vehicle or between front and rear support units in order to raise one side of the vehicle while at the same time lowering the other side or to move the front part of the vehicle in the opposite direction from the rear end accordingly. However, one disadvantage of this system is that additional stabilizers are needed to guarantee the required passive roll stiffness of the vehicle and thus safe operation of the vehicle.
German Published Patent Application No. 20 48 323 describes a device for the stabilization of the vehicle superstructure against a curve gradient in which a hydropneumatic suspension replaces the stabilizers, and a pressure medium is conveyed as a function of the cornering directly to the pistons of cylinder-piston units, in particular hydropneumatic springs, which are connected between the wheels and the vehicle superstructure, so that the cylinder-piston unit allocated to the wheel on the inside of the curve is shortened in the sense of lowering the vehicle superstructure, and the cylinder-piston unit allocated to the wheel on the outside of the curve is lengthened in the sense of raising the vehicle superstructure.
One disadvantage of the device described in German Published Patent Application No. 20 48 323 is that additional add-on springs are required, but they have a negative effect on the overall roll stiffness of the vehicle. In addition, another negative effect of both devices described above is that other passive suspension elements are present in the vehicle in addition to the active hydropneumatics, resulting in a passive roll stiffness against which an active device must work, but this is unfavorable from an energy standpoint.
It is therefore an object of the present invention to provide an active device for the suspension and for roll stabilization of motor vehicles so that additional springs and stabilizers are not necessary.
The above and other beneficial objects of the present invention are achieved by providing a device for the suspension and for roll stabilization of motor vehicles as described herein.
Through specific coordination of piston surfaces and piston ring surfaces in combination with an active displacement unit, the hydropneumatic device for the suspension and for roll stabilization of motor vehicles can yield the full required vertical and roll stiffness simultaneously. This hydropneumatic device for the suspension and for roll stabilization of motor vehicles thus provides the complete suspension of the vehicle, so that no additional springs or stabilizers are needed, which thus offers advantages with regard to cost, weight and installation space in addition to the energy benefit.